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SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0243 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z No changes are needed to the D2 Fire Weather Outlook. See previous discussion below for more information. ..Thornton.. 09/02/2024 .PREV DISCUSSION... /ISSUED 0218 AM CDT Mon Sep 02 2024/ ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0243 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z No changes are needed to the D2 Fire Weather Outlook. See previous discussion below for more information. ..Thornton.. 09/02/2024 .PREV DISCUSSION... /ISSUED 0218 AM CDT Mon Sep 02 2024/ ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE CENTRAL TO NORTHERN ROCKIES... ...SUMMARY... A risk of isolated strong to severe storms capable of producing gusty/locally damaging winds will exist from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis and Discussion... A weak upper trough providing cooling aloft and modest flow will move across the northern Plains on Wednesday, while a cold front moves across the Dakotas, trailing southwestward into the central High Plains by 00Z. High pressure will remain over much of the East, providing stable conditions there, and enhancing southerly winds over the Plains ahead of the front. In general, a plume of 50s to lower 60s F dewpoints will spread north toward the front late in the day. Scattered storms will first form over the higher terrain across eastern MT, WY, and into central CO, with steep lapse rates and modest deep-layer shear favoring marginal hail. Storms will also form along the cold front, from eastern CO into the Dakotas. Backed low-level winds and veering winds with height may support a few supercells, though multicellular clusters will also be likely as winds aloft are on the marginal side for better organized storm structures. Still, favorable time of day and steep low-level lapse rates will likely favor gusty to locally severe gusts as activity spreads across the northern and central Plains through the evening. ..Jewell.. 09/02/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE CENTRAL TO NORTHERN ROCKIES... ...SUMMARY... A risk of isolated strong to severe storms capable of producing gusty/locally damaging winds will exist from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis and Discussion... A weak upper trough providing cooling aloft and modest flow will move across the northern Plains on Wednesday, while a cold front moves across the Dakotas, trailing southwestward into the central High Plains by 00Z. High pressure will remain over much of the East, providing stable conditions there, and enhancing southerly winds over the Plains ahead of the front. In general, a plume of 50s to lower 60s F dewpoints will spread north toward the front late in the day. Scattered storms will first form over the higher terrain across eastern MT, WY, and into central CO, with steep lapse rates and modest deep-layer shear favoring marginal hail. Storms will also form along the cold front, from eastern CO into the Dakotas. Backed low-level winds and veering winds with height may support a few supercells, though multicellular clusters will also be likely as winds aloft are on the marginal side for better organized storm structures. Still, favorable time of day and steep low-level lapse rates will likely favor gusty to locally severe gusts as activity spreads across the northern and central Plains through the evening. ..Jewell.. 09/02/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE CENTRAL TO NORTHERN ROCKIES... ...SUMMARY... A risk of isolated strong to severe storms capable of producing gusty/locally damaging winds will exist from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis and Discussion... A weak upper trough providing cooling aloft and modest flow will move across the northern Plains on Wednesday, while a cold front moves across the Dakotas, trailing southwestward into the central High Plains by 00Z. High pressure will remain over much of the East, providing stable conditions there, and enhancing southerly winds over the Plains ahead of the front. In general, a plume of 50s to lower 60s F dewpoints will spread north toward the front late in the day. Scattered storms will first form over the higher terrain across eastern MT, WY, and into central CO, with steep lapse rates and modest deep-layer shear favoring marginal hail. Storms will also form along the cold front, from eastern CO into the Dakotas. Backed low-level winds and veering winds with height may support a few supercells, though multicellular clusters will also be likely as winds aloft are on the marginal side for better organized storm structures. Still, favorable time of day and steep low-level lapse rates will likely favor gusty to locally severe gusts as activity spreads across the northern and central Plains through the evening. ..Jewell.. 09/02/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE CENTRAL TO NORTHERN ROCKIES... ...SUMMARY... A risk of isolated strong to severe storms capable of producing gusty/locally damaging winds will exist from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis and Discussion... A weak upper trough providing cooling aloft and modest flow will move across the northern Plains on Wednesday, while a cold front moves across the Dakotas, trailing southwestward into the central High Plains by 00Z. High pressure will remain over much of the East, providing stable conditions there, and enhancing southerly winds over the Plains ahead of the front. In general, a plume of 50s to lower 60s F dewpoints will spread north toward the front late in the day. Scattered storms will first form over the higher terrain across eastern MT, WY, and into central CO, with steep lapse rates and modest deep-layer shear favoring marginal hail. Storms will also form along the cold front, from eastern CO into the Dakotas. Backed low-level winds and veering winds with height may support a few supercells, though multicellular clusters will also be likely as winds aloft are on the marginal side for better organized storm structures. Still, favorable time of day and steep low-level lapse rates will likely favor gusty to locally severe gusts as activity spreads across the northern and central Plains through the evening. ..Jewell.. 09/02/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE CENTRAL TO NORTHERN ROCKIES... ...SUMMARY... A risk of isolated strong to severe storms capable of producing gusty/locally damaging winds will exist from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis and Discussion... A weak upper trough providing cooling aloft and modest flow will move across the northern Plains on Wednesday, while a cold front moves across the Dakotas, trailing southwestward into the central High Plains by 00Z. High pressure will remain over much of the East, providing stable conditions there, and enhancing southerly winds over the Plains ahead of the front. In general, a plume of 50s to lower 60s F dewpoints will spread north toward the front late in the day. Scattered storms will first form over the higher terrain across eastern MT, WY, and into central CO, with steep lapse rates and modest deep-layer shear favoring marginal hail. Storms will also form along the cold front, from eastern CO into the Dakotas. Backed low-level winds and veering winds with height may support a few supercells, though multicellular clusters will also be likely as winds aloft are on the marginal side for better organized storm structures. Still, favorable time of day and steep low-level lapse rates will likely favor gusty to locally severe gusts as activity spreads across the northern and central Plains through the evening. ..Jewell.. 09/02/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE CENTRAL TO NORTHERN ROCKIES... ...SUMMARY... A risk of isolated strong to severe storms capable of producing gusty/locally damaging winds will exist from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis and Discussion... A weak upper trough providing cooling aloft and modest flow will move across the northern Plains on Wednesday, while a cold front moves across the Dakotas, trailing southwestward into the central High Plains by 00Z. High pressure will remain over much of the East, providing stable conditions there, and enhancing southerly winds over the Plains ahead of the front. In general, a plume of 50s to lower 60s F dewpoints will spread north toward the front late in the day. Scattered storms will first form over the higher terrain across eastern MT, WY, and into central CO, with steep lapse rates and modest deep-layer shear favoring marginal hail. Storms will also form along the cold front, from eastern CO into the Dakotas. Backed low-level winds and veering winds with height may support a few supercells, though multicellular clusters will also be likely as winds aloft are on the marginal side for better organized storm structures. Still, favorable time of day and steep low-level lapse rates will likely favor gusty to locally severe gusts as activity spreads across the northern and central Plains through the evening. ..Jewell.. 09/02/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE CENTRAL TO NORTHERN ROCKIES... ...SUMMARY... A risk of isolated strong to severe storms capable of producing gusty/locally damaging winds will exist from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis and Discussion... A weak upper trough providing cooling aloft and modest flow will move across the northern Plains on Wednesday, while a cold front moves across the Dakotas, trailing southwestward into the central High Plains by 00Z. High pressure will remain over much of the East, providing stable conditions there, and enhancing southerly winds over the Plains ahead of the front. In general, a plume of 50s to lower 60s F dewpoints will spread north toward the front late in the day. Scattered storms will first form over the higher terrain across eastern MT, WY, and into central CO, with steep lapse rates and modest deep-layer shear favoring marginal hail. Storms will also form along the cold front, from eastern CO into the Dakotas. Backed low-level winds and veering winds with height may support a few supercells, though multicellular clusters will also be likely as winds aloft are on the marginal side for better organized storm structures. Still, favorable time of day and steep low-level lapse rates will likely favor gusty to locally severe gusts as activity spreads across the northern and central Plains through the evening. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN ROCKIES AND INTO THE EASTERN GREAT BASIN... ...SUMMARY... Scattered strong storms with isolated severe may produce damaging wind gusts and marginal hail from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... On Tuesday, an upper trough will weaken as it moves from the Northwest into the northern Rockies, providing cooling aloft and increased mid and high level flow. To the east, a large upper trough will exit the northeastern states, with height rises over the north-central CONUS. At the surface, a weak cold front will move across the eastern Great Basin, ID, western WY and southwest MT by early afternoon, increasing lift/convergence. Elsewhere, a moist air mass will remain from TX eastward across the Gulf Coast, with scattered non-severe storms likely. ...Eastern Great Basin into the Northern Rockies... As heating accelerates and cooler temperatures overspread the region, steep lapse rates will yield a large area of thunderstorms, developing relatively early in the afternoon, from much of UT into southwest MT. The strongest instability with 500 to 1000 J/kg MUCAPE will be roughly from far northern UT into MT, where temperatures aloft will be coolest. Deep-layer effective shear will increase to around 40 kt, especially across ID, MT, and northwest WY, which will aid cellular storm mode and hail potential to around 1.00" in diameter. Otherwise, scattered storms across the entire area will produce outflows, with progressive clusters of storms producing strong to locally severe gusts. A few storms may make it as far east as western SD by late evening, with generally decreasing intensity after sunset. ..Jewell.. 09/02/2024 Read more

000
ABPZ20 KNHC 021726
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Mon Sep 2 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster D. Zelinsky

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1201 PM CDT Mon Sep 02 2024 Valid 021700Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON AND SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... An active day of fire weather is anticipated across the Pacific Northwest, Great Basin, and portions of the High Plains. Morning 12z observed soundings from SLC (Salt Lake City, UT) and LKN (Elko, NV) indicate precipitable water values around 0.60". Midlevel moisture should increase through the day ahead of forcing for ascent with a midlevel wave currently just offshore in the Pacific Northwest. A mix of isolated to scattered wet/dry thunderstorms is expected by the afternoon with potential for new ignitions from lightning. In addition, Critical conditions are likely in the lee of the Sierra across Nevada and in the High Plains. No changes have been made to this forecast. See previous discussion for more information below. ..Thornton.. 09/02/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Mon Sep 02 2024/ ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1201 PM CDT Mon Sep 02 2024 Valid 021700Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON AND SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... An active day of fire weather is anticipated across the Pacific Northwest, Great Basin, and portions of the High Plains. Morning 12z observed soundings from SLC (Salt Lake City, UT) and LKN (Elko, NV) indicate precipitable water values around 0.60". Midlevel moisture should increase through the day ahead of forcing for ascent with a midlevel wave currently just offshore in the Pacific Northwest. A mix of isolated to scattered wet/dry thunderstorms is expected by the afternoon with potential for new ignitions from lightning. In addition, Critical conditions are likely in the lee of the Sierra across Nevada and in the High Plains. No changes have been made to this forecast. See previous discussion for more information below. ..Thornton.. 09/02/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Mon Sep 02 2024/ ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more